In the past, various types of apparatus for enclosing the cargo bed of a pickup truck, travel trailer or the like vehicles have been proposed. Many such apparatus include a mechanism for moving an enclosing top between a low profile traveling position and a high profile use position. While several types of such cargo bed enclosing apparatus have been built and sold, in general, the raising and lowering mechanism of such apparatus have had one or more disadvantages. Specifically, the most common mechanisms used to move a cargo bed enclosing top include a series of telescoping members located at the four corners of the cargo bed. The telescoping members have been raised and lowered by one or the other of various types of pneumatic, hydraulic and mechanical systems.
Pneumatic systems, of course, have the disadvantage that they require a compressor to provide a source of pneumatic power. Further, pneumatic systems are, inherently, relatively weak. While hydraulic systems are substantially stronger than pneumatic systems, they require a hydraulic reservoir and, like pneumatic systems, a plurality of coupling tubes or conduit. And, because hydraulic fluid viscosity changes with temperature, such systems may become difficult to operate at low temperatures if an incorrect hydraulic fluid is used. Further, such systems are relatively expensive.
Mechanical systems, in the past, have often included extendable, flexible mechanical members mounted inside of telescoping tubes for extending and retracting the tube members. Such systems, of course, produce very limited amounts of mechanical force. Finally, proposals have been made to utilize cable/sheave mechanisms in combination with rotatable shafts to extend and retract telescoping tubes. Such systems, of course, also can produce only a limited amount of mechanical force because slippage between the cables and the sheaves occurs when large mechanical forces are attempted.
It will be appreciated from the foregoing brief discussion of prior art mechanisms for raising and lowering cargo bed tops, that, in general, such mechanisms (particularly prior art mechanical mechanisms) produce relatively limited amounts of force. Further, many such mechanisms, particularly pneumatic and hydraulic mechanisms, require a substantial number of supporting mechanisms, all of which are expensive and subject to deterioration and breakage. For example, pneumatic and hydraulic seals are subject to deterioration and often frequent replacement.
In addition to the foregoing disadvantages, many prior art cargo bed raising and lowering systems, in particular mechanical systems, are open to the atmosphere. Consequently, such systems are subject to the effects of dust, dirt, water and other deteriorating items. As a result such mechanisms are subject to jamming and rusting whereby such mechanisms, at best, are unreliable.
Therefore, it is an object of this invention to provide a new and improved apparatus for covering the cargo bed of a pickup truck, travel trailer or other vehicle having a cargo bed.
It is also an object of this invention to provide a new and improved apparatus for covering the cargo bed of a pickup truck, travel trailer or the like vehicle that includes a mechanism for moving an enclosing top between a lower traveling position and an upper use position.
Because of the limited amount of weight that can be lifted by prior art top raising and lowering mechanisms, in the past only relatively lightweight tops have been raised and lowered. This limitation has a number of disadvantages. For example, the top cannot be used to support relatively heavy items, such as cabinets, storage containers and the like. As a result, such items cannot be moved from a lower inaccessible position to a raised accessible position in one step.
Thus, it is a further object of this invention to provide a mechanism for raising and lowering a relatively heavy top from the cargo bed of a pickup truck, travel trailer or the like.
It is yet another object of this invention to provide a new and improved mechanical mechanism for raising and lowering a relatively heavy enclosing top from the cargo bed of a pickup truck, travel trailer or the like that is enclosed to prevent moisture, dirt and the like from entering the mechanism and detrimentally affecting the operation of the mechanism.
It is a still further object of this invention to provide a top suitable for enclosing the cargo bed of a pickup truck, travel trailer or the like adapted to support one or more storage containers mounted beneath the top such that the storage containers can be moved between a concealed position whereat they are enclosed by the side walls of the cargo bed to an accessible position whereat they are above the side walls of the cargo bed.